A free app for Android, by Scarlett Systems.

Musician is a metronome, tuner, and piano app for learning music that is designed to be simple, yet functional in assisting everyone from the budding guitarist to the seasoned classical musician. The app’s built-in metronome helps you improve your musical accuracy by training you to master your tempo, while the tuner helps you stay in tune. The piano keyboard is also a useful tool for you to use to help you practice your scales and identify tricky spots in your music.

The app is made up of a small number of instruments, scales, chords, and piano keys, and is designed to be easy to learn and use.